Multiple pronged double-ended fastener



June 26,. 1951 L. B. GREEN 2,553,132

7 MULTIPLE PRONGED DOUBLE-ENDED FASTENER Filed Feb. 5, 1949 3 Sheets-Sheet 1 June 26, 1951 B. GREEN I MULTIPLE PRONGED DOUBLE-ENDED FASTENER Filed Feb. 5, 1949 3 Sheets-Sheet 2 AN 1 III IIllllllllllll A INVENTOR.

. June 26, 1951 B. GREEN MULTIPLE PRONGED DOUBLE-ENDED FASTENER 3 Sheets-Sheet 5 Filed Feb. 5, 1949 L 6 M, /M/E/VTOR Fis. 15

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Patented June 26, 1951 -MULT IPLE' PRONGED DOUBLE-#ENDED "rAsTE ER z LeeyB qreen, Lakewood, ,O hio Application-Eebruary 5, 1949, Serial N o.'74,776

G-CIa m l :Myinvention relates to-securing elements more particularly adapted to the making of 'joints between articles madeof wood'or likepenetrable materials.

;More particularly, my invention relates to an improved highly efiicientform of securing element of the general type previously disclosed' 'in IfiycO- pending prior application for patent,'Seria1No. 737,494, filed March 27th, 1947, now abandoned,

and "Serial No. 47,232 filed September 1st,".I948, also'now abandoned, being a continuation in'part of the former, and a continuation of the latter of'my aforesaid previously filed applications. An objectofmy invention is toprovidea :securing element of the aforesaid general type,

which can be manufactured at a minimum ost,

butwhich is highlyefficientin operation.

Another'obj ect of my invention is to provide an improved securing element of the aforesaid type,-wherein "the points of the prongs are not necessarily sharpened or bevelled therebyloweririg the-cost of production, and at the same-time are so formd as to be more efiicient inusel invention, and-to an improved method'ofmanufacturing said element, and by reference to the accompanying specification which is descriptive of the embodiment shown'in the said drawings.

In the drawings:

Fig. '1 illustrates 'in side elevation, a securing v elementwhichv is .a preferred embodiment of my invention; v .Fig..2 isa plan view oftheembodiment shown in'Fig. 1;

Fig. 3 illustrates in side elevation'three'typical prong end formations which .may be advantageously employed in the making of securing elements as shownin Figs. 1 and 2 to adapt said elements for the makingof joints between articles of different materials having different degrees .of .penetrability by .said prongs, [the degree of taperingof prong tipsas, shown, ,being substantially exaggerated to emphasize a principleof prong formations.

' ,Fig. 4 is a side elevational view of a strip ,of

steelorlike suitable-materialadapted to'be rolled ,to substantially cylinderelike form to form anfelement.substantially asshown in Figs.. 1 and,2

QFig. 5,.is substantially .a vpla'nometric view .of

Fig. :6 is.a view similar .to thatof Fig. .1,.but

:showing the tubular .element in aform having .relatively more prongs and wherein thediameter of :the element is greater thanitslongituditlal:di-

.mension Fig; '7 is. a .plan view ofthe element otFig. .6

Fig. 8 is a side elevational .view 'of.the;.e1ement of 1Eigs. .1 and .2 together with twowertically'gmaterspaced blocks-of wood in positionto bejoined :byth'e said elements and showing, by dottedjlines,

:ailo'wermost set of .pron'gs thereof .embeddedin the-lowermost block of wood;

Figli 9 is .a View similar to that of ;Fig.;8, but showing the uppermost block 20f wood .there'of iforced downupon the'pointed endsof the uppermostsetof prongs .of the elementof Fig. 8qto (cause said set of prongs to penetrate andibeembedded :in the uppermostwood block',. the.sec.uring element being, herein, shown by dotted lines.

:Fig. 10' is a top plan view of the securingtele- -ment-as inFig. 8 taken from the plane Ill-l0, -of Fig.-3;

Fig. 11 is a View substantially of the char :acter of that shown in .Fig. 9, :but additionally showing :a joint-reinforcing :elem'ent projected Ithroug'h-the uppermost piece of wood-andinto. the lowermost piece of wood, the saidreeinforoing element being in the formof a wirenail which extends axially through .the securing .element .which iszlikethatof Figsql,2,.8 and 9;

Fig. '12 illustrates a :metallic; strip .of a differ- :ent ,qform ,from that shown in iliigs, 4 gand '5. f.or subsequent rolling into the form of ;a tube ithezmanneriof thatshown'in- Figs.;1;and17fto provide another embodiment,of .my; invention;

jFig. 13 is arside. elevational jVifiW' of .anoppositely -.pronge.d securing element of thesame general type as -that-shown in Fig. but differing therefrom win .that the apical portions 1 of, the; op-

positrglydirected serration notches are idispo sed placed, said lines generally. correspondingtos'iinillai'lines'placedginFig. 15; Fig. .717 is "a transverse section taken-0n the i el qiiofrigns;

1mg. 1 8 .is a view otherwise similar to. that of stantially transversely straight form, which supports a relatively outturned tip portion. i

More particularly, the drawings show my invention as embodied in band-like articles having,

varying forms, different of which are shown by different figure of the drawings. A first form of my invention is shown in Figs. 1 and 2 and a modification is shown in Figs. 6 and 7 which is of I the same general form, and as shown, said modification is different only in having a difierent relationbetween its longitudinal and diametrical dimensions, whereby it is somewhat shorter with respect to its diameter, and is provided with a relatively increased number of prongs for each of the pair of prong sets, which comprise its opposite longitudinal end portions.

vAll of the prongs of either of the prong sets are relatively laterally offset with respect to the prongs of the other set, to such an extent that the apex 'l of any of the prongs 4 of one of the prong sets is in alignment with the apex 9 of the corresponding V-shaped serration notch it] which is disposed between a pair of prongs of the relatively oppositely extending set of prongs; the

apices of the prongs and notches may preferably be slightly blunted, as shown in Figs. 13 and 16, such blunting being of advantage in the manufacture of the article.

' The ofisetting of prongs is illustrated particularly for a prong indicated at 4a whose base comprises equal aligned base portions X and Y which are shown by dotted lines and the particular notch Ill indicated between the prongs 4b which are of the relatively oppositely extending set, as its apical portion in bisecting relation to the said dotted line base of the prong 4a. The same general relationship exists when the strip of Fig. 4 with bent tips as shown in Fig. 5 is rolled into the form of a band as in Figs. 1 and 2 as best shown by the middle prong of the upper set of Fig. 1 which is based on the dotted line A-A and the notch Ill indicated between prongs of the opposite set having its apex in bisecting relation to the base of the prong 4.

The same relationship exists for all or the prongs with respect to oppositely extending nearest adjacent prongs, whose bases are all in alignment and partially overlapping as shown.

'Figs. 13 and 1'7 show another embodiment of the invention wherein a pair of oppositely extending sets of serration notches have their apical end portions so extended as to cause those of the one set of notches to be disposed in relatively overlapping relation to those of the other set, as distinguished from the showing of the first illustrated first form of article wherein the inwardly extending notches disposed between prongs of both sets terminate substantially at the medial waist line A-A of the article; Figs. 12 and 18 each show a fragment of a fiat serrated strip having outturned tips as in the former embodiments but differing therefrom in that one set of prongs, and of course the notches between the prongs of such set are of increased longitudinal and. lateral dimensions with respect to the other or upper set of prongs, as shown; at the same time the oppositely extending notches of the article of Fig. 18 may or may not be in overlapping relation as in Fig. 13 and are all shown as terminating at a waist line A"-A" which coincideswith the base line for each and all of the prongs.

One of the prongs of the longer set is shown at 40 and a prong of the shorter set is shown at 4|. The axis of bending for the prong tips being shown at 50 and 55 respectively for the longer and shorter prongs, as in Fig. 18, and in this embodiment by construction lines (1 and d as later more fully described, a structural difference between this and the other embodiment later herein described is emphasized.

The strip of Fig. 18, having its lateral end edges properly cut as shown, for instance in Fig. 5, and with the tip portions bent in the same manner, may then be rolled into the form of a band, as before described, to provide a third embodiment of my invention. .After rolling a steel strip as shown in Fig. 5 to the form of a band as in Figs. 2 and 7, the relatively lateral side edges of the strip are disposed in contiguity to provide a seam which is indicatedat S.

The band-mm article as shown in initial form before use, in Figs. 1 and 2, or in 6 and 7, is provided with two sets of substantially V-shaped prongs 4, which extend in relatively opposite directions from a waist region indicated by the line A-A of Fig. 1, there being a relatively inverted V-shaped notch space, such as at It, disposed between each adjacent pair of prongs either set.

Preferably, in the article of Figs. 1, 2, 6 and 7 the form and dimensions of each notch corresponds to the form and dimensions of each of the prongs 4, with the exception that the tip portions 2, of all the prongs are bent, at 5, outwardly with respect to the longitudinal axis of the article and with respect to the tip supporting body portions of the prongs.

The prong body portions located between the outturned tip portions and the base of each prong, which is located in the longitudinal middle region of the band which includes the line AA of Figs. 1, 5 and 16, retain their substantially planular form during the rolling operation.

For a reason later herein more fully set forth, the prongs d of the tube-like elements which are designed for the making of joints between materials of different degrees of hardness, or reversely expressed, of different degrees of penetrability, are bent about the transverse axis which is indicated at 5, to a lesser angularity with respect to the substantially straight main body portion 40 of the prongs. In the form shown by the intermediate drawing of Fig. 3 the tubular article shown is thus adapted to make joints be- .tween wood or lflre bodies of harder or less penetrable material, than is the tip as shown by the drawing at the left side of Fig. 3, whereas the prong shown at the right side of Fig. 3 is adapted for joining of bodies of much softer wood or the like, as a result of bending the prong ends, about the, axis 5, to the relatively greatest degree shown in any of the drawings of Fig. 3.

With respect to the variation of thickness of the prongs 2 proceeding from their bending axis 5 to their extreme ends, as shown, for emphasis, somewhat exaggerated in Fig. 3, I find that this tapering, so-called, is the direct result of the bending of tip portions on the transverse axis at 5. and results because of the elongation of the 5 portion of the-prong material which :is tnearest the more upwardly disposed side z of the.:prong tin-and whichis atthe opposite sideof the prong from the outwardly facing surface which contains the bending axis :5.

Bending of the tip portions 2 of the prongson an axis which is indicated at .5, Fig. 3, and at H65 in Fig. :14 and as indicated elsewhereincthe drawings, is preferably performed upon a Hat oppositely serrated strip, as for example, .is shown in Fig. 4,1toachieve .the resultant iform showninFig. 5.

Preferably after such bending. operation, the strip of Fig. 5 isthen'rolled.toitsbandelike form with the tips 2 directed'laterally"outwardlygto dispose .its end edges in .contiguity ;to afford-a seam S asshownin'Figs. 2 and '7.

When rolled to the band-like orltubeelikejform of Figs. 1,2, sand 7 the :abrupt'bend shown at .5 or H15, achieving the purpose of out-turning each prong tip, also hasa restraining influence on any tendency of the prong to be curved transversely during the rolling operation.

As later more specifically, hereinreferred to, transverse, curvilinear bending of thejmain body portion of each prong is. more completely. avoided as a result of so prolonging the inward'extent 10f all .of .the notches ill or H0 of both sets so that small distortion areasare provided at the base .of each and every prong wherein a small amountof permissible distortional bending is invited and automatically occurs during the rolling of .a strip to the described band-like form.

Such distortion areas are of small extent and are shown at a: respectively in Figs. and .16 for exemplary particularprongs which are :'respectively designated as 104a and 4a.

As shown for the said particular prongs each of which happens to be located in the uppermost set of prongs in each of Figs. 15 and 16, the distortion areas :r allocated to such; particular prongs are disposed between the transversely extending, longitudinally medial waist line A-A and the relatively upper pair of dotted lines e which are above said Waist line.

Such pairs of dotted lines e substantiallyxrepresent the uppermost extent of distortional bending along the base of each said exemplary prong, and divergently extend from common point 9a, at the apex of that notch which is vertically and longitudinally aligned with any said particular prong, to relatively corresponding points in the opposite side edges of the said particular prong. The direction of extent of ea'ch of said pair of lines e is such as to make the line extend normal to the prong side edge, which it meets.

Therefore, as a result of the provision of said small distortion areas at, at the base of each prong body and the abrupt outbending of the prong tips, whichoccasions resistance to forces tending to transversely bend the prongs during the rolling any of the .forms of metallic strip having opposite sets of prongs, each prong having the tips bent at 5, it is'found that'the main body portions of all of the prongs remain substantially transversely straight, to achieve the important function of permitting the prongs to bend radially outwardly from'the band axis duringthe hereafter described intended use of the-article, substantially as best indicated in Fig. 17.

As shown in all of the drawings, the length of the prongs is substantially in excess Mom and one half (1 times their width at the base line --AA and forsatisfactory results for most contemplated usesthe dimension of the width of a prongat .the :baseline should .not be .inpexcess oflwvo-thirds /3) of the dimension representing the longitudinal extent of the prong although with thislimitationithe prongs may be.made in varying lengths to best adapt them for eificient results for any contemplated use, although :I prefer, as shown, .that the base width :of the prongs .be .approximately equal to one-half that of theirlengths.

Each of Figs. 1, 2, 4, 5, .8, 9, 10 and .11, illustrate a tube-like securing element :having two -.oppositely extendingsets 20f prongs each having ten prongs,.and Figs. Sand 7 show asecuringelement which has sixteen prongsin'eachset; but .otherwise, vthedescription of the embodiment of Figs.'1 and 2 applies equallyzto the embodiment ofjFigs.t6 and '7. More or fewer prongs maybe used, and the size of the prongs may be varied, :but. inrevery case, for most purposes, I prefer that the medially-disposed apex ofeach serration. notch proceeding from the opposite end of the tubelike article should bisect the base of the prong pointing from the opposite end of the element.

Referring now to Fig. 8, by dotted lines, a /2 endzportion of the element of Fig. 1 is shown as being submerged in a block of wood ii, vandiby reference thereto, the prong bending enect achieved by driving the laterally bent prong tips into .the material of the block H, is illustrated in comparison with the upper set of prongs which .have..not,.as yet, been forced into penetratin relation with the superposed second block of wood shown at !3. The lowermost set of prongs of Fig. 8 will be understood to have been driven .into the body ofthe material of the block I 5 until .the zone indicated by the line AA, in Fig. 4 whichrepresents the level of the apices of the serrations of which that shown at w is representative, is disposed at the level of the surface of the block.

The driving of the said lower set of prongs of Fig. .8 may be accomplished in any known way but preferably through use of a tool substantially like either of those disclosed-in my co-pending application, Serial No. 62,033, filed November 26, 1948, the disclosures of which are thus incorporated herein by reference, for a full under standing of the preferred method of drivingthe .first set of the prongs into a penetrable body such as the block'of wood i I of Fig. 8.

:surfaces in abutment and with the apices of all "serrations 1!! of the pronged joining element be 'ing preferably disposed in theplane of the abutted surfaces, and as shoWn,the goining operation re sults in such deformation ,of all prongs that both'upper'and-lower sets of prongs are spread outwardly ina clenching 'or; mushrooming formaiti'on.

When the prongs are being forced 'intopenetrating relation with the wood or other pene- 'trable body,-the resistance offered. by the material'of'thebody effects a camming action upon the inner surfaces of theprong ends .2 .and then to:a-somewhat lesser extent upon the inner surfaces of -the;main body portions of the prongs, *so as to'cause'the prongs to be directed more or less laterally, to a degree depending upon the initial degree of inclination of the prong tips 2, and also dependent upon the relative degree of resistance which is offered to the penetration of the prongs, as a result of the degree of hardness possessed by the material of a penetrable body, such as shown at l I and/or l3.

In Fig. 9, the securing element of my invention is shown only by dotted lines and is not at all visible from the exterior of the joined bodies and this is often of great advantage, in cases where a smooth presentable exterior surface is desired, an instance being where the joint is between elements of furniture.

Another very important advantage possessed by the preferred embodiment of my invention wherein the apices of all serrations are located'in the same circumferential zone which is so extremely narrow as to be here considered to be approximately on a line, or in a plane, is that each of the prongs is free to bend proceeding from its pointed tips to the prong portion at its base, which is located in the said plane or line AA.

The prongs t are transversely straight in all portions between their extreme tips 2' to the region of their bases, in the said line or plane A-A. They are not so curved transversely so as to cause them to be more or less trough-shaped or channel-shaped, which formation would cause the prongs to very strongly resist bending.

Since all of the prongs of m improved element are completely V-shaped and the serration notches extend from both ends of the element to the same medial zone or line, both sets of prongs are readil completely embedded in the joint between two relatively abutted wood or like bodies with the ends of the serration notches disposed precisely at the junction of the abutted body faces, with each adjacent pair of side edges respectively of a pair of adjacent prongs of the same set thus embracing portions of the wood or other joined body material into which the element is submerged.

My improved element, as above described and as shown possesses no continuously annular midportion which extends in the longitudinal direction between the bases of the two sets of oppositely directed prongs, which, if present, would cut and isolate a dowel-like piece of the body, and by virtue of the substantially V-shaped notched spaces between adjacent portions of a set, avoids the making of a completely annular cylindrical cut of a penetrable body, as would occur if portions of the side edges of adjacent prongs of the same set were substantially interengaged, or laterally separated only Very sli htly.

A highly important advantage of my improved element resides in the fact that when the strip as in Figs. 4 and 5 is rolled into the generally tubelike form as in Figs. 1 and 2 or as in Figs. 6 and '7, substantially all portions of each prong, proceeding from one side edge to the opposite side edge thereof, remain transversely straight, and the prongs therefore being not transversely bowed, are in the best possible form to promote a desired degree of outward bending, when forced into the aforesaid penetrable body, to effect the clenching formation, of prongs.

The operation of rolling the cut strip, alone, without any other operation, as previously set forth, places the prong body portions of each set in the angularly related planes of the sides of a polygonal tube, and although both sets of prongs proceed from a region between the relatively displaced sets of prongs which includes the apices of the serration notches, the main body portion of every prong remains transversely flat throughout the rolling operation which converts the strip to tubular form.

The polygonal outlines of the inner and outer surfaces of the body portions of the two sets of prongs are relatively rotatively displaced a distance equal to /2 the width of a prong base.

The fact that adjacent oppositely directed prongs have overlapping bases does not result in objectional distortion of the base portion of any of such prongs, so as to noticeably detract from the ability of every prong to be readily driven completely into penetrating and clenching relation with a wood or like penetrable body. All portions of the prongs are free to bend outwardly, to a most efficient degree, to achieve the clenching function, during forceful penetration of the prong into a penetrable body, the bending being more pronounced in portions of the prong which are located nearest the pointed ends, but the prongs are properly bendable to a most desirable degree, and in their regions indicated at a: in Figs. 15 and 16, which are disposed substantially contiguous to their base lines.

The slight distortion of the metal in the regions extending between successive notch apices, is not sufiicient to detract from highly efdcient clenching bending of the prongs, nor to prevent penetration of such regions of distortion as at .r, into a wood or other penetrable body during the making of a joint, since such distortion is extremely slight and is so gradual and the distorted parts are so restricted in area and are so disposed as to pass unnoticed either by outward appearance or in the operation of application.

Although as above stated, the substantially planular body portions of all prongs of each set are so disposed as to define the sides of a polygon whose sides correspond to the number of prongs in a set, being transversely straight, and the two sets being rotatively off-set with respect to each other, as an entirety, the joining element of my invention, by casual inspection, appears to closely approach a cylindrical outline even where a particular embodiment may contain only a relatively small number of prongs in each set.

My improved element does not involve the presence of oppositely extending prongs disposed in longitudinal alignment, which construction would require that each pair of oppositely extending prongs be joined by laterally extending connecting bridging portions designed to extend between adjacent pairs of oppositely extending prongs, which would either prevent, or, at least, render impracticable the complete embedding of the element in a joint, oreven if completely embedded by an objectionably increased driving force would provide a non-functional and deleterious cutting or indenturing means for portions of the wood bodies which be disposed within the elements between the prongs.

Again, it is to be noted that my element is preferably made of very thin sheet metal, the preferred thickness being such as preferably not to exceed ee of an inch for elements not exceeding inch in the longitudinal direction, but it will be understood that for penetration of the prongs into material of different degrees of hardness the 1thickness of the prongs is subject to some varialOIl.

Within the spirit of my invention, I contemplate sometimes making the prongs of one of the two oppositely extending sets longer than the prongs of the other set and also, Icontemplate sometimeszproviding-ythe; prongs 01 one set. withtips 2 bent. outwardly atza different angle than. arethe prongsotthezothert set as, .for. instance, when j oining-:apieceof. lessipenetrableor harder wood to a second. piece. of. more-penetrableor. softer wood.

Again, within the spirit. of my invention, although I.- have hereini illustrated my improved elements: as. being in. an approximation of. a cylindrical. outline; for some special purposes. this form.may be. widely departed from sincemy inventionis susceptible of incorporation. in ele ments preferably of. substantially tubular. outline which may be=oval, or. more: closely triangular-or rectangular.

Referring, nowparticularly to. Fig; 11. wherein a jointemploying an element of my invention is shown insubmergedpenetrating relation with:re.- spect. to two joinedpieces. of. wood and wherein a wire nail 55 is projected through one of thewood pieces, axially through the element, and intothe other. wood piece, the; expedient of subsequently driving a nail tore-inforce. the joint. achieves the further-objective of applying radially outwardly directed stress. tothe inner faces. of the outwardly bent prongs. 4, whereupon, the holdingpower of the element of my invention is. increased. toza substantial; degree, and at the same time, the subsequent nailing operation may be achievedwithoutthesame degree of tendency tosplit the wood body, since the tendency of such anailtosplit thewoodinto whichit is driven. is restrained and minimized by the efiect' of the constraining pres.- ence of my improved element.

Again, Icontemplate sometimes prolonging the longitudinal extent of the serrations. so thatserrations as disclosed in my said first filed application for. patent, of either set are projected somewhat beyond those of the other set so that longitudinally considered, the:serrations=of the two sets will overlap to. some extent, and I findthat such an embodiment" is quite efiicient in use:

Elements of my invention which are other embodiments thereof and are above described are illustrated in my said first filed co-pending. application and I propose herein to claim my invention insufficiently broad terms. as to cover variations. from the said embodiments herein illustrated,.and described.

With respect to the varyinginclination of the prongtips shown in the three examples of Fig. 3, which. are not drawn to scale,.a degree of tapering at the tip ends being. exaggerated for emphasis, consideration'beinggivento the resistivity of thewood or other body'mat'erial of theiarticles intendedto be. joined by the'joining element, my preferance is to so. bend theprongtips about the axis 5', in the manner. illustrated in Fig. 1'4. which shows the major outermost'portions of two: prongs of opposite. sets,. so. that. a. prolongationof the plane L--L of the outer side surface 40 will intersect the extreme tip end 2a or preferably so that the corner l0! at the prong tip will be located laterally within such extended plane, the reason being to make the entire prong stiifer during the period when the tips are ready to enter, are just entering, or have just entered the material of the body which the prongs are to penetrate, so as to avoid undue bending of the prongs by the resulting thrust of driving the element, since the inclined inner surface Z of the prong tips is relied upon, through a camming action, to spread the prongs laterally outwardly as the prong tips penetrate the body material, below the surface of the body.

In Figs. 12 and 18, a strip of the general nature of that. otfigs; 4. 931C? iseshownto. illustrate-- another. embodiment of my. invention. wherein. the prongs 40 at one-end of theresultingtube may be. of double-size. both in the: longitudinal.- and transverse. directions, with.- respect. to the'oppositely extendingsetof prongs 41, at-theother. end of. the; tube, which is'later formed by the rolling of the. strip. in the. manner previously described andshown.

Respectively at.55.- and atz50, theprongs-of. the two sets are adapted for. outward bending of their tips or the nature. otzthoseshownat. 2 in theforegoing embodiments.

Inthe form.shown,.in.Fig. 12,.the base of. each prong, 45- extends laterally to an extent-twice. as great as the base of any of the oppositely directed prongs M and the apices 44 and 41 of one or. said prongs; 60. and a directly oppositely extending prong. s s, of the set M, areinlongitudinal alignment. with each other.

The apices 34. of allof the. successive prongs 4i] are. thus, preferably, longitudinally aligned withapices of. the alternate of the oppositely directedset. of the relatively smaller setof prongs 4|, and also. theapexofthe-pointed ends of.such an alternate set of the smaller prongs M are thus preferably disposed. in. longitudinal alignment with the apexof theserration notch which isdisposedibetweenthe saidlpair. of thelarger prongs.

The embodiment of Fig. 12. may be advantageously used. in suclispecial;environments where the lcngset of'prongs. will" be projected. into the end of'a post, or other. thick body; of. penetrable material to which it. is desired" to joinathinner penetrable. body by the shorter and narrower prongs; it will'be apparent to those familiar with the art of making wood or likejoints, that the embodiment shown in Fig;.1'21l'ends itself to many analogous purposes; one being where thebody receiving'the prongs 40 is ofsofter materialthan is the material of the body which receives. the prongs' ll.

Since inthe embodiments of my invention the prongs of the two sets are relatively so. circumferentially displaced that notches of the: one set are longitudinally aligned with preferably cor;- respondingly'di'mensioned prongs of the otheriset and due to the fact that all of the'prongs have their lateral edges converging'in straight lines to dispose their edges-in V-f'orm; when one of the articles of' my invention is driven-or pressed to'penetrating relation to a Woodor like penc trable body in any of the two shown such as Figs. 8 to 11- inclusive; It is important to note that asindicated by the dot-dash referencelines al asshown in Figs. 15 and 16 that these lines passing from" the tips of one set of prongs may be passed" centrally through the base portions of prongs of the other'set' to theapicesof the-other prongs sa-that a straight liheof drive stress exists within the edges of the prongs, transmitting penetrating power from the outer portions of the prongs of one set to the tips of the prongs of the other set as, for instance, when placing one of the tube-like articles of my invention between two wood bodies such as the bodies shown at II and I3 in any of the Figs. 8, 9 and 11 and then forcing the two wood bodies together to occasion simultaneous penetration by each said set of prongs into a respectively diiferent' one of the bodies.

With respect to the embodiment of Fig. 18 where the bases of the prongs of the lower set are of double width, the similar pressure lines 01 are passing from apices of the smaller-prongs to the apex of a large prong of the other set. In

such a case, also, there is a vertical line of stress passing medially-through aligned prongs of the two sets as indicated by the line (1'.

It is important for the transmission of penetrating pressure communicated between the ends of each prong particularly where the article is being placed into penetrating relation with relatively hard wood bodies, that the line of pressure LL which is in the same plane as the more outward face 40 of the prongs shall not pass to the rear of the rearmost tip corners I01.

Having thus described my invention, I am aware that numerous and extensive departures may be made without, however, departing from the spirit of my invention and the scope of the appended claims.

I claim:

1. A unitary article of manufacture adapted for joining a pair of wood or like resistively penetrable bodies together in flatwise abutting relation to each other with opposite end portions of the article disposed in penetrating submerged relation in the said bodies, comprising a tube-like band of thin sheet metal whose opposite longitudinal ends are alike inwardly serrated to afford two sets of oppositely directed V-shaped prongs, each set having its prong tips disposed at a different longitudinal end of the band, a relatively oppositely directed V-shaped serration notch of the same shape and size as the prongs being disposed between adjacent pairs of said prongs, the apices of the notches of the two sets being alternately disposed in circumferential alignment in the longitudinal middle of the article, at least the inner surface of the tip of each prong being flared outwardly to afford outward clenching bending of the prongs when forced into any said penetrable body, each prong being substantially straight sided and transversely flat.

2. The article of manufacture substantially as set forth in claim 1, characterized by the apices of said prongs being blunted.

3. The article of manufacture substantially as set forth in claim 1, characterized by the said tip portions of at least a substantial number of the prongs of each set being out-turned obliquely to the axis of the band.

4. The article substantially as set forth in claim 1, characterized by said prong tips being obliquely out-turned relative to the axis of the band to dispose their apical end edges at a slightly increased distance from said axis, said distance being not greater than that dimension which corresponds to the thickness of the metal of the prong.

5. A unitary article of manufacture adapted for joining a pair of wood or like resistively penetrable bodies together in flatwise abutting relation with opposite end portions of the article submerged within a different of said bodies, comprising a strip of sheet-metal having opposite relatively parallel longitudinal end portions which are correspondingly serrated as to afford two sets of oppositely directed V-shaped prongs, each thereof having its side edges disposed in relatively convergent relation throughout the longitudinal extent of the prongs, with a serration notch of the same size and shape as the prongs disposed between each adjacent pair of prongs and being oppositely longitudinally directed with respect to said prongs, said strip being rolled to tube-like form to form a seamed band, each of said sets of prongs respectively extending from a circumferential common waist-line of the band to a difierent of the longitudinal ends thereof, said prongs having relatively short tips which are obliquely out-turned, all said notches of the respective sets extending from a common circumferential waist-line of the rolled article to respectively opposite longitudinally ends of the article, each prong of both sets being longitudinally aligned with the apex of a serration notch extending from the other end of the article, and the adjacent edges of each adjacent pair of prongs defining that notch which is disposed between them, and said notch edges being free of any portion disposed in re-entrant relation to such notch.

6. The article substantially as set forth in :claim 5, characterized by the radial distance of the apical ends of said prongs from the axis of the article being in excess of that of the portions thereof which are located at its said waist-line by a distance which is not substantially greater than the thickness of the sheet metal of said band.

LEE B. GREEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 800,243 Popple Sept. 26, 1905 805,212 Litz Nov. 21, 1905 1,669,847 Zimmerman May 15, 1928 1,724,610 McArthur Aug. 13, 1929 2,128,844 Myer et al Aug. 30, 1938 2,236,926 Surface Apr. 1, 1941 2,277,956 Coffman Mar. 31, 1942 FOREIGN PATENTS Number Country Date 61,998 Germany Apr. 23, 1892 4,016 Sweden Dec. 10, 1892 188,331 Great Britain Feb. 29, 1924 128,555 Great Britain Apr. 29, 1919 494,131 Great Britain Oct. 20, 1938 

